Waterproof board and method of preparing same



Feb.24, 1931. H.| Ev|- l 1,793,810

WATERPROOF BOAR) AND METHOD OF PREPARING SAME Filed Sept. 17, 1928 l Patented Feb. 2,4, v193.1

y UNIT-151Dv s'ra'rrish PATENT OFFICE HAROLD L. LEvIN, F NUTLEY, NEW JERSEY, ASSIGNOR To THE FLIN'rKoTE comu PANY, or BOSTON, MASSACHUSETTS, A CORPORATION oF'MASsAoHUsnTTs WATERPROOF BOARD AND METHOD OF PREPARING SAME Application filed 1September 17, 1928. Serial No.' 306,477.

This invention relates to improvements in plaster board commonly comprising an inner cementitious core of stucco, plaster, or the like, having outer surface coverings of absorbent paper.

More particularlymy invention relates to [Waterproofv plaster boards of the type indi- Y cated and to improved methods of manufacturing the same.

Numerous attempts have been made in the art to produce Waterproof plasterboard. These generally have concerned themselves Awith the incorporation of a Waterproofing medium as a separate layer' in the plaster board structure. In some cases this layer of Waterproofing material has been interposed between the opposed surfaces of the inner core and the covering pliesrbut this expedient has usually resulted in an insecure bond between the surfacing ply or plies and the plaster core. In other cases, in order to provide a better bond between the `covering sheets and the plaster core, the waterproofing layer has been applied over the exterior of the surfacing ply or plies. This procedure, however, results in a smooth Water-repellent surface to which it is very difficult to apply plaster, the plaster not being readily adher ent to such a surface. Furthermore, in either' of the foregoing practices, it the Waterproofing material is applied to the structure prior to the complete Setting and hardening of the corematerial, there is a further difficulty in that the Waterproofing layer interferes with the complete setting and hardening of the core. In orderto eliminate the foregoing objections, Vit has also been proposed to apply to the usual plaster board structure having absorbent Surface plies, an

additional ply secured to one of the absorb.

ent surface plies by'means of an interposed l film of waterproofing substance so that the structure could be waterproor` and yet have Va surface thereof sufficiently absorbent to enable the plaster to be adherent thereto. This last type of plaster board, however, :is costly to manufacture, not only because it entails the use of more material, but because of the manufacturing problems that must be .plied to the surface ot the board.

In accordance with one embodiment oi my 'invention I may employ the usual forni of absorbent sheets as the suriace coverings and intel-pose between the opposed surfaces of the sheets and the inner core, a layer of waterproofing material carried in an aqueous medium. More speeificallyfin accordance with my invention, I utilize a dispersion of Waterproofing;l material carried in an aqueous the Water being in the externalphase of the dispersion land the waterproofing substance. being dispersed as finely divided particles comprising the internal phase, By the use of n'aterprool'ing material in the 'torni of a dispersion, as thus briefly described, I find that the. penetration of the water contained in the dispersion into the porous surfacing sheet and the non-repellent relation between the dispersion and the green unset material of the core, permit the surfacing sheet or sheets to be securely bonded to the core without 1nterfering with the proper and complete setk ting of the cementitious material ot' the core and yet leaving the outer surface of the cov eiing sheet or sheets in an absorbent condit1on for the reception'and permanent retention of plaster thereon. The dispersion which 4I may use in carrying out my invention may be one of any of thetypes Well known in the art. Preferably, the waterproofing material dispersed in the aqueous vehicle 1s ot a b1- tumiuous character and is substantially nonfluid at normal temperatures. I find that asphalt having a melting point of between and 200 F. is .suitableV for the purposes ot my invention. Tlul bituminous material may be dispersed in accordance with any desired method known to the art, the dispersing agent comprising any one of a number of I I' I\ 0 materials known to serve this function, s uch as soap, sulphonated oils, clayspf various types, gums, metallic oxides and powders or the like. The dispersions produced with these different types of dispersing agents vary in vtheir stability` over quite a range, those made with material such as soap being generally of less stable character than those made with materlals such as clays, metallic v teristic property, these dispersions permit the moisture of the core to be'evaporated prior to complete coalescence of the dispel'- sion film, for as long as any water or moisbe appreciated, of course, that dispersionsof Vthe type set forth are generally miscible With ture is present in the core, the dispersion film in contact with the core will not coalesce sufliiciently1 to-seal in and prevent the complete elimination ofwater from the core. A dispersion of this character suitable for-the pur poses of my invention may comprise generally from 40' to60% of the bituminous material as the dispersed base, 2 to 15% of theedispersing agent and the balance water. It will water in substantially all proportions, and

hence, if the consistency of the dispersion is too thick for applying the same in the manner to be hereinafter described, Water may be added to thin the'dispersion to the desired consistency.

I' have s hown in the drawings a conventional arrangement' for carrying o ut the foregoing embodiment of my invention. As here 1llustrated, one of the surface coverings 10 isvr fed from a roll l1 and another similar sheet 20 is fed from a similar roll 21, the two sheets being broughtl together in opposed spaced relation for the reception of the cementitlous i 'material of the core therebetween, in accordance with the usual practice. At any convenient time prior to the introduction'of the cementitious material between the opposed coverin sheets, I apply to the upper surface of the 5i aqueous dispersion of waterproofing material of the character described,- this material being supplied by any convenient means as indicated at 12. The-dispersion thus deposited on the sheet may be leveled or doctored oif to provide alayer 'of uniform thickness, as by means of a suitablev doctor blade 13.A A s1m1larlayer of waterproong mateeet 10 a relatively thin layer AAof an any convenient way. vI have shown forthis purpose, in Fig. 1, a supply box 22 containing the dispersion material of desired consistency, and a rotatin roll 23 partially submerged inthe materlal in the supply box and arranged to pick up a. layer of the material as it rotates and apply the same in the form of a film of uniform thickness to the surfaceof the sheet 20. Ifdesircd, the dispersion` may be similarly applied by means of a roll to the sheet 10, or suitable spraying equipment may be used in' lieu of t e means conventionally shown. It will be appreciated by those skilled in the art that as the water is eliminated from the aqueous dispersion, the dispersed particles coalesce to form a continuous film. of the waterproofing material, the relative speed with which the coalescence ofy the dispersed particles is initiated, depending somewhat upon the type of dispersing agent used in `producing the dispersion. The plastic material for the inner core 1s introduced between the opposed 'coated surfaces of the covering sheets while the dispersion coating material is still wet and before it has coalesced to any substantial extent. The supply of the plastic material is indicated at 30, a sluice or similar 'feed means 31 being shown for delivering the same from the supply means to the space between the covering sheets. The illustration in' the drawing shows the plastic material as being introduced vsubstantially immediately after the covering sheets are coated with the dispersion material but this showing is for purposes of illustration only and the introduction of the plasticmaterial between the covering sheets may be delayed more or less, although it should be introduced prior to any substantial coalescence ofthe dispersion coatings.

After'the plastic material has been applied, the structure is then conveyed to suitable drying means to assist in setting the plaster core as well as in effecting coalescence of the dispersion films between the core and the covering sheets. Inasmuch as the waterproofing material is carried'in an aqueous medium and is thus miscible with the plastic material of the core, the coalescence of the interposed layer of f Waterproofing material does not in anyway interfere with the setting of the core material or the permanent bonding o f the covering sheets ,to the c ore, and-in fact the usev of the dispersion material enables 'a more secure bond to be attained between the core and the 'covering sheets. After the board is dried, the core set and the interposed layerof dispersion coaleseed, the board may be advanced to further desired stages of treatment-such as trimming, cutlao ting ofthe continuous sheet into boards of desired length, et cetera.`

,Cates the inner core of plasterl or stucco, the letters I), thc interposed layers of coalescedV Waterproofing material, and the letters c, c indicate the surfacing sheets attixed thereto.

VIn accordance with another embodiment of my invention I may apply the dispersion inaterial on the exterior of the surfacing plies instead of between the surface or surfaces of the core and the inner face of the covering ply or plies. The advantages of my invention may be realizedsubstantially fully as well with this type of structure since the nature -of the dispersion material as already described permits the complete evaporation of' Water from the core' to take place through the porous surfacing ply or plies and the dispersion layer, the latter being transformed into a coalescentiilm only after substantially `complete removal of the water contained therein and in the core. It is to be further noted in this connection that the utilization of this embodiment of my invention does not present the diiiiculty that usually arises when applying waterproofing material 'such i as asphalt in its normal condition, to the exterior of the surfacing ply orV plies, namely, that the -surface thereof is too smooth for the proper retention of plaster thereon.` I find that in this embodiment of my invention the waterproof film' resulting from the complete removal of water from the core and the dispersion layer, possesses a suiclent degree of tooth or keying property to enable plaster to stick thereto with adequate permaneney.

In carrying out this embodiment of my invention the procedure may consist in forming the plaster board structure in the usual Way and themwhile the core material is still green and unset, applying to the outer surfaces of the coveringsheets, by means of a roll or doctor blade or by sprays, thedispersion material in aulayer of desired thickness. Alternatively, if desired, the dispersion material may be applied to the external surface ofthe covering sheet or sheets prior to the application of the green plaster material between the opposed inner surfaces of the sheets. The wet structure .with its outermost layer of dispersion material may then be conducted through any convenient stage for drying out the water and moisture of the inner core and the dispersion layer.

I have not shown in the drawings, the arrangement for carrying out this embodiment as it will be obvious to those skilled in the art that lit would be merely necessary in this instance, to transpose the dispersion applying device 12, 13 and Q2', 23-to any convenient point following the application of the core material, instead of arranging the same, as

shown in Fig. l, ahead ofthe delivery of the Core material between the surfacingl sheets. Another advantageous 'feature of this cmbodiment of my invention resides in the fact that the dispersion material may be made oi a light colorablelmse such as resin, colorableasphalts or the like, so'that the dispersion may be colored with any desired pigments or. metallic powders to provide a decorative surface finish for the board structure which would enable the latter to be employed as a wall hoard instead of as a base for subsequently applied plaster.

n It will be appreciated by those skilled in the art that I should not regard it as a departure from my invention if the dispersion material were applied both intcriorly and extcriorly of the surfacing sheet or sheets, as obviously the advantages already pointed out would accrue to a structure'made in this way.

Having thus described my invention, itwill be evident to those skilled in the art that numerous changes and modiiications may be made therein without departing from the spirit or scope of the invention as defined by the claims hereunto appended.

I claim as my invention:

1. The process of manufacturing plaster board, which comprises forming a core of plastic cementitious material and combining therewith a covering sheet of absorbent material having one of its surfaces coated with alayer of an aqueous dispersion of bituminous material.

2. The process of manufacturing plaster board, which comprises coating one surface of an absorbent. sheet with an aqueous dispersion of bituminous material, forming a core of plastic cementitions material, and prior to substantial coalescence of said dispersion applying said sheet to the core with the coated surface thereof in contact with the core. l

3. The process of manufacturing plaster board, which comprises coating the opposed surfaces of spaced absorbent plies of paper with a film composed of an aqueous dispersion of bituminous material, and prior to substantial coalescence of said dispersion interposing cementitious material between the coated plies to form a core therebetween. 4. The process ofmanufacturing plaster board, which comprises coating the opposed lsurfaces of spaced absorbent plies of pa er with a film composed of a dispersion of icoalesced from an aqueous dispersion of said bituminous material. v 6. Plaster board, comprising an inner core of plaster or the like, a covering sheet 5 of absorbent material bonded thereto with an interposed layer of bituminous material coalesced from' jan aqueous dispersion of said bituminous material. l 7. Plaster board, comprising an inner core of plaster or the like and outer covering plies v of absorbent` material aiiixed thereto', there being a continuous film of bituminous material coalesced from an aqueousdispe'rsion containing said bituminous material, interposed-between said core and the opposed surfaces of the plies. In testimony whereofI aiix my signature.

HAROLD L. LEVIN. 

